Even with increased focus on those experiencing homelessness, the number of homeless families continues to rise, with the demand for temporary shelter so high that many cities are unable to meet the needs of these families. The majority of these families are headed by single mothers, many of whom struggle with substance use and mental health issues. These struggles are in addition to meeting the basic needs of themselves and their children. No study has documented an effective approach for intervening with homeless substance abusing mothers with children. Research attention towards identifying efficacious interventions for this population which address the multiple needs of these families is thus considered an important focus for reducing significant individual and social costs associated with substance use and homelessness. The current study utilizes an ecological systems approach as the theoretical base for the proposed treatment. The overarching goals of the current treatment development study are to first identify targets and processes of intervention desired by homeless mothers and then pilot test a novel manualized intervention focused on improving treatment success of this special population. In Stage 1a, information from the multi-method assessment and focus groups with N=30 homeless mothers will guide modifications to an integrated intervention that includes housing, case management and the Community Reinforcement Approach. The final manual resulting from this important study will address the multiple needs of homeless mothers, including basic needs and substance use/mental health problems. The intervention will be tested in a nonrandomized pilot (N = 15) in which interview and self-report methods will be used for data gathering. Follow-up will be conducted at 3 and 6 months post baseline and the intervention will be modified based upon the process and outcome analyses. Finally, the revised intervention will be tested in Stage 1b in a randomized pilot study involving 60 women and children assigned to the project intervention (N = 30) or treatment as usual (N=30) and followed at 3, 6, and 9 months post- baseline. In the randomized pilot study an effect size will be computed for use in informing a larger, randomized Stage II trial. This project utilizes existing efficacious models of drug abuse treatment to generate valuable new information critical to treatment services delivery for a special population of substance abusers. Since homeless substance abusing women and their children are at increased risk for a variety of adverse outcomes, improved maternal and child outcomes may produce substantial health-care benefits to the women, their children, and society at large. The findings from this study will serve as the foundation for the refinement and implementation of a promising intervention for drug-addicted homeless women and children that can then be tested for efficacy in a Stage II trial. PUBLIC HEALTH RELEVANCE: Effective interventions are critically needed to improve the lives of substance abusing homeless mothers and children in their care. The current proposal seeks to address this gap through modifying and evaluating an ecologically based treatment that includes housing, case management and the Community Reinforcement Approach. Such research attention is needed in order to reduce the significant individual and social costs of continued substance use, mental health and homelessness among these vulnerable women and children.